Immersible oxygen and temperature measuring probes, usually supported for immersion by a molten metal consumable, ablative paperboard tube attached to a sensor and covering and protecting a support pipe or lance that carries the sensor electrical leads. Such lances have been used for at least half a century. In recent decades the probes have often contained a stabilized zirconia oxygen cell and a platinum-rhodium immersible thermocouple. Some such probes have included a sand filling but have included one or more gas impermeable components such as ceramics, plastics, potting cements, silicones or the like in their designs believed to be necessary to protect the measuring devices from unwanted exposure to heat, pressure, hot gases and hot gas movements. Such gas-contact preventing components were heretofore thought to be a necessary protective feature of the oxygen and temperature measurement systems in view of the high temperature melts involved, typically 3000° F. or 1700° C., even though immersion times are limited to about 10 seconds.
Notwithstanding the long history of use of thermocouple and oxygen probes, which sometimes include a metal sampling mold, such probes have heretofore sometimes been subject to fluctuating readings and thus are unable to consistently provide the quick, accurate, repeatable oxygen content and temperature readings required for today's demanding manufacturing processes. The interruption, pressurization and restraint of the movement of even trace amounts of combustion products or moisture emanating from paperboard or from coatings or materials used in the probe or gases dissolved in the melt and existing in the probe often result in errors in the readings, often causing the need for retesting thereby interrupting and increasing production time and therefore increasing production costs. To date, combination immersion testing, sampling and oxygen content determining devices have been found to perform with inadequate speed and inconsistent accuracy. In light of these shortcomings, a need has continued to exist for improved probes and testing devices.